Today's wireless systems are mainly based on a fixed frequency allocation to a specific service. For example, the band around 900 MHz and around 1800 MHz are exclusively reserved for the use of Global System for Mobile (GSM). Other bands are reserved for other kinds of wireless communication and navigation systems.
Among the other types of wireless systems, for example, are those using mobile radio standards such as GSM, Universal Mobile Telecommunications System (UMTS), code-division multiple access-2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Enhanced Data rates for GSM Evolution (EDGE); Multi-Carrier Code Division Multiple Access (MC-CDMA), and non coordinated communication systems such as WLAN (Wireless Local Area Network) or WPAN (Wireless Personal Area Network) adapted to work for example according to a UWB (Ultra Wide Band) technology. Also, WIMAX devices (Worldwide Interoperability for Microwave Access) are fixed wireless devices, operating for example with a bandwidth of 20 MHz at a central frequency of 3.5 GHz. The co-location within the same device of different communication modules adapted to operate according to different communication protocols or standards, has been already contemplated.
However, in such existing systems, the normal receiver circuitry or means are used for performing a spectrum sensing. In other words, each communication module is sequentially switched into a scanning mode and can then get an idea of the frequency allocation in its surrounding. However, this sequential scanning is in general slow and thus very time consuming. Furthermore, the time resolution of this conventional method is limited due to the limited sampling time of the used systems.
There is a need to scan a complete frequency band of interest in a single operation without changing the operational mode of the wireless device. There is also a need to improve the resolution of the spectrum analyzing.